The invention relates to devices for assembling together side by side the concrete slabs constituting highway surfaces or similar areas such as airport runways, at their junction zones, said zones being in the form of substantially flat and vertical interfaces or cracks.
By "slabs" is meant in the present description not only slabs properly speaking, produced individually and juxtaposed side by side during the construction of the highway, but also pieces of such slabs created by local cracking thereof, such cracking being either started voluntarily by creating special grooves in the upper surfaces of the slabs, or involuntarily because more especially of bad weather or defects of homogeneity in the foundation layer on which the slabs rest.
The problem which the invention proposes solving is that of the lateral coupling together of the slabs in question at the level of their zones of join so as to make possible slight mutual horizontal movements of the slab edges defining these zones perpendicularly to the mean surfaces of said zones, movements generated more especially by temperature variations in the slabs, but preventing the mutual vertical movements of said edges: these movements are in fact causes of deterioration for the edges in question and the vertical displacements which result therefrom are disagreeable for the users of vehicles travelling along the corresponding highways.
To ensure such a mutual coupling of slabs, it has already been proposed to place cylindrical connecting pieces of vertical axis into complementary cylindrical housings made astride the zones of join concerned, these pieces being elastically compressible in the horizontal direction perpendicular to the mean surface of the zone of join and adhering respectively on the two edges of slabs which define this zone so as to join them together vertically.
In patent FR No. 2 412 651, it was proposed to provide the connecting pieces of the kind in question with two rigid semi cylindrical half shells which are joined together vertically, but not horizontally, by a rigid inner key adapted to slide horizontally, are urged horizontally apart by elastic means and have two facing peripheral bearing surfaces joined together by a seal.
The solution which was proposed in said patent for forming the connecting pieces considered has a certain number of disadvantages, in particular the following:
the need to use different elastic materials for forming the element which ensure respectively the elastic expansion and the sealing,
the smallness of the mutual bearing surfaces ensuring the vertical transfer of loads between each half shell and the inner key, and so the short life-span of these pieces, which are subjected in use to incessant hammering
the absence of a horizontal abutment adapted to limit the crushing of the elastic masses providing the elastic expansion.